Wrinkle measuring device



Jan. 8, 1963 N. w. PANDELL ETAL 3,072,012

WRINKLE MEASURING DEVICE Filed April 28, 1959 2 Sheets-Sheet 1 INVENTORSNESTOR W. PANDELL HAROLD R. BELLINSON Y 4x22! My,

ATTORNEY Jan. 8, 1963 N. w. PANDELL ETAL 3,072,012

WRINKLE MEASURING DEVICE Filed April 28, 1959 2 Sheets-Sheet 2 INVENTOR5NESTOR W. PANDE LL 4 HAROLD R. BELLINSON ATTORNEY United States Thisinvention relates to a method and a device for measuring surfacecharacteristics of a web of flexible material, and more particularly toa method and device for measuring surface irregularities such asWrinkles of a Web of flexible material. The present application is acontinuation-in-part of our application Serial Number 746,- 808, filedJuly 7, 1958, and titled Wrinkle Measuring Device, now abandoned.

With the recent growth in the wash and wear fabrics and related wash andwear clothing industry, a need has arisen for an accurate and precisestandard of performance for the various fabrics described as wash andwear, "minimum care, or drip -dry.. These terms are only generalindications of the characteristics of the fabric imparted to it by thefinish and indicating generally that the fabric is relatively smooth andwrinkle free after washingand without ironing. The performance of thesefabrics, after washing and drying without ironing, varies in that thefabrics have differing frequencies of wrinkles and differing sizes ofWrinkles depending upon the particular finish used and the care withwhich it is applied. This variation of performance has caused someunfavorable consumer reaction and is a threat to the wash and wearindustry.

To date, to the best of our knowledge, no method or device foraccurately measuring surface wrinkles, or sim- 3 ilar surfacecharacteristics of a flexible web, is available which would permit aneffective evaluation of fabrics or the establishment of a standard ofperformance for wash and wear fabrics. Comparisons heretofore have beenmade entirely by visual observations or other non-precise methods. Asthe method and device of the present invention were developed inconnection with measuring surface irregularities or wrinkles in flexiblematerials for establishment of a standard of performance for wash andwear fabrics, our invention will be described in this preferredembodiment. However, it will be re'cognizedthat the present method anddevice are equally useful in meas? uring or evaluating surfacecharacteristics other than wrinkles, and therefore that it is useful inconnection with flexible Webs other than fabrics, and even for measuringor evaluating characteristics of inflexible surfaces as will beexplained hereinafter.

.The problem presented by the increasing popularity of wash and weargarments is a problem of determining the performance in terms of thesmoothness of the surface of the wash and wear fabric after drying andwithout ironing. This in turn requires that accurate standards beestablished and, in accordance with the instant invention, that accuratemeasurement of the surface irregularities in the Wash and wear fabric beobtained for comparison purposes.

The present method for measuring the surface characteristics, andparticularly the wrinkles, of a flexible web includes the steps of firstprojecting an enlarged profile of a line across the surface of theflexible web, then quantitatively measuring the irregularitiescontinuously along the line' profile, and then comparing the measurementwith standard, such as a measurement of the profile with the wrinklesremoved. This method provides a scientific measurement of the surfaceirregularities or wrinkles and eliminates errors which arise throughmental calculations and comparisons. It also eliminates subjectiveerrors which arise because of color variations caused by shades andpatterns, and by thickness or variations in the weave of the fabric.This method also eliminates the effects of long range trends such asdrape or roll effects in the web from the measurement.

According to the device of the present invention, the flexible web ispositioned on a mandrel having the desired curvature to obtain a crownor crest extending along a line across the surface in order to reveal aninner edge of the flexible web. A beam of light is directed from asource toward the ridge line of the crest formed across the surface toproject a profile shadow of the surface of the web. A receiving screenintercepts the projected profile and includes means to record acharacteristic of the surface such as the frequency and size ofwrinkles, or to compare the projected profile with a standard. In thepreferred em bodiment, two photoelectric cells are positioned to receivetwo separate points on the profile and to generate a difference voltage.The projected profile is caused to move across the two receivingphotoelectric cells to obtain a continuous signal along the length ofthe projected profile. Suitable computer means are connected to receivethe generated signal and to record the continuous sum of such readingsfor comparison or evaluation.

We have been concerned with the so called wash and wear problem, andhave invented a method of measuring surface characteristics of aflexible web in accordance ing smoothness of the fabric and believe itpermits an evaluation of wash and wear performance. Thus, our devicepermits an accurate comparison to be made between the surfaceirregularities in a piece of fabric in a relaxed condition after Washingand therefore containing Wrinkles, and this same piece of fabric whichhas been tensioned to remove wrinkles. Thiscomparison is independent ofthe weave or finish and eliminates large roll or drape effects fromconsideration. Also, construction or surface irregularities such asslubs, that is, a knot in the thread from which the fabric is woven,fuzz, lint, dust or random projections of fibers, are eliminated fromthe evaluation since a comparison of readings with the same fabric ismade and only the wrinkles are removed by tensioning. By using the imageor shadow profile of the exposed line surface of the fabric, we alsohave eliminated the problems. of differing colors and shades orother'surface effects in fabrics. .This contrasts with previous sug-vgestions concerning the use of reflected light, see through opticalsystems, or other similar devices and is. an important feature of ourinvention.

An object of the present invention is to measure av sur-. facecharacteristic of a flexible material.

A further object of the present invention is to measure surfaceirregularities of a flexible web. having surface ir regularities ofvarying frequencyand amplitude.

A further object of the present invention is to provide a method forevaluating wash performance of wash and wear fabrics with scientificaccuracy and without regard to normal surface characteristics or tocolor, weave, or drape of the fabric.

Still another object of the present invention is to provide a devicewhich will permit measurement or evaluation of surface characteristicsof a flexible web without mental calculations or visual observations.

Other objects and advantages of the present invention will be apparentfrom the following description together with the drawing, in which:

FIG. 1 is a schematic plan view of a device for measurwith the presentinvention;

FIG. 2 is a side view of a device shown in FIG. 1 with some of theelectrical elements deleted for clarity;

FIG. 3 is an enlarged detailed view of the irregular shadow cast by aprofile of the sample of fabric and sensed 3 by the photoelectricreceiving means in accordance with our invention;

FIG. 4 is a partial side view illustrating a tensioning arrangement forthe fabric specimen; and

FIG. 5 is a partial end view illustrating a tensioning arrangement forthe fabric specimen.

In describing the preferred embodiment of the present invention, afamiliarity with a special analytical technique of statistical methodwhich is known as the mean square successive difference will be helpful.This is for the reason that our invention analyzes a mass of data whichis in effect successive differences in the surface irregularity of apiece of fabric, by employing the said technique. Thus, in terms ofstatistical method, one recognized method of minimizing the effect of along ranged trend where the variation in the mean is gradual (that iswhere a linear or non-linear trend is shifting the mean of a population)is to estimate the standard deviation from differences. The equation forthe means square successive difference is:

where S is the estimate of the population variance, or

of the standard deviation squared and i refers to the temporal orspatial order of the observation X.

Another related analytical method found to be useful in measuringwrinkles is to obtain the sum of absolute successive difference. This isexpressed by the equation:

This method of calculation can also be used to estimate, a, thepopulation standard deviation. Although not as efficient as thecalculation involving squares, its accuracy is entirely adequate when alarge number of observations is available. Its advantage in thisinstance is that it permits a great simplification in computer circuits.

Furthermore, if the number of observations, n, is always constant, andif the purpose of the analysis is simply to make comparisons, then it isnot necessary to divide by n -l, and only necessary to obtain this sum.

This is the basis of the computer circuits in the preferred embodiment.

' Correlating the above to our invention, the small wrinkles or surfaceirregularities of small magnitude are distinguished from the long rangetrend (drape or roll effects in the fabric) by using an analog computerwhich in effect calculates the mean square successive difference, or ina second instance, above, the sum of the absolute successivedifferences. This is believed to be logical for the reason that what thelayman terms wrinkles are those surface irregularities which are mostapparent to the human eye. These are the small wrinkles rather than thelarge roll, drape or similar effects.

Briefly, our inventive device permits the utilization of two separatebut simultaneous observations of a piece of fabric. These observationspreferably are of two adjacent areas in the shadow profile of a lineacross the fabric. For this purpose, the two photoelectric cells arejoined electrically so as to feed to an analog computer an electricvoltage which represents the difference between two observations. Theanalog computer in one case may electrically square this difference, andan entire series of differences, and store the sums thereof electricallyin a condenser. When the sum of absolute difference is used, the voltagedifferences generated by the two photoelectric cells may be positive ornegative and therefore a so-called absolute value unit is used to feedonly positive values directly to the computer which sums and recordsthem. The final summation is recorded electrically for a given piece ofwashed fabric in a relaxed condition. The same fabric again is measuredand recorded after tensioning the fabric to remove surface irregularitycaused by wrinkles and the difference between the two readings is usedto establish an index of performance for the fabric. By experience,precise standards of wash and wear performance then can be related tothe mathematical values of these differences. For example, a differenceindex between 0 and 1.0 might be excellent, whereas a difference between10 and 20 might be poor.

With the above background in mind, reference now should be had toFIG. 1. Firstly, an electrical lamp bulb 1%, together with a mirror 11and one or more condensing lenses such as 12 and 13, provide a source oflight the beam of which is identified by the numeral 14. This beam oflight is caused to shine tangentially across the top surface of a sampleof fabric P which is draped so as to be perpendicular to the beam. Thebeam then progresses through a control aperture 15, through focusinglenses such as 16 and 17, and on to a perpendicular shadow screen 18. Asshown in FIG. 3, the shadow S which is thus formed on the screenmagnifies the surface irregularities of the fabric F.

Behind the shadow screen 18, we place two photoelectric cells, 19 and20. These may be either self generat ing selenium cells or photronicphotoelectric cells, the self generating selenium cells here being thepreferred embodiments selected for purposes of illustration. As shown inFIG. 3, these photoelectric cells are arranged to sense the contour ofthe magnified shadow S cast by the surface irregularities on the pieceof fabric F.

For example, an electric circuit 21, 22 connects the photoelectric cells1? and 20 via a switch 23 to an analog computer. This analog computer isshown as a box because it is a common item commercially available on themarket. In a device for recording the sum of the absolute successivedifferences, for example, the analog computer might include a DC. powersupply, a number of operational preamplifiers, a multiplier section anda number of operational manifolds to which is added an integrator forsumming the successive computations which in this case comprises acapacitor for accumulating successive values. These elements are allcommon commercial items. The computer is of a type which has an inputsection and an output section. By an electrical effort, the analogcomputer accumulates the sum of successive electric voltages received bythe input section and transmits this sum to the output section. Thus, asshown in FIG. 1, a voltmeter 24 can be joined to the output section ofthe analog computer and the dial of the voltmeter calibrated to yieldreading directly proportional to the accumulated sum of the electricvoltages which are received by the input section of the analog computer.

Referring more particularly to the photoelectric cells 19 and 20, itwill be noted that these cells are electrically connected so that theanode of one cell is joined to the cathode of the other cell. Theseconnections cause the voltages generated by the individual cells tooppose one another. The resultant voltage transmitted through thecircuit 21, 22 thus is the difference between the voltages generated bythe individual cells as hereinafter more fully will be explained.

Referring now to the electric components associated with our invention,we have indicated a source of alternating current with the letters A.C.This source of current first is passed through a voltage stabilizingdevice 25., Three separate circuits are connected to the output of thevoltage stabilizing device 25. The first of these, 26, provides a sourceof current for the electric lamp 10. The second of these, 27, provides asource of current for the computer. The third of these, 28, actuatesmechanism associated with an electric motor M to cause the previouslymentioned piece of fabric F to traverse or to move perpendicularly backand forth in light beam 14- as now will be described in more detail. Theelectric motor M is a reversible split phase induction motor having separate start and rotor terminals 29 and 30 respectively. A

double throw reversing switch R is interposed in the electric circuitfor the motor M so as to allow the motor to be run in either directionin order to effect a traversal of the fabric F in either directionacross the light beam 14.

A holding solenoid 31 is provided for the normally open switch 32 in themotor circuit. In addition, a push but.- ton starting switch 33 islocated in the primary electric circuit for the motor M. In general,these elements and their associated elements define means for moving thefabric F in a direction parallel to the surface of the fabric as nowwill be explained in more detail.

As shown in FIG. 1, the rotor of the motor M drives a pulley over whichruns a belt 34. The belt 34, in turn, rotates a second pulley and thusactuatcs a gear reduction train 35. It is the function of the gearreduction 35 to rotate a screw 36 upon which are mounted two collars 37and 38 together with suitably mounted followers. Rotation of the screw36 in one direction causes the collars to carry a fabric supportcylinder 39 in one direction, whereas a reversal of the motor M, andthus the screw rotation 36, will cause the collars 37 and 38 to move thesupport cylinder 39 in the opposite direction. It is the supportcylinder 39 over which the fabric F is draped for the measurement of thesurface irregularities and it is an important feature of the inventionthat the support provides a line exposure of the surface of the fabricto the light beam. This casts a profile type of shadow on the screen aswill be appreciated.

The collar 38 carries a cam 49 which is positioned to intercept,selectively, the following wheels of the switches 31 or 42. The latterthus define limit switches which stop the traversal of the supportcylinder 39 at a preselected exact position each time a piece of fabricis scanned by the light beam.

Similarly, the normally closed switch 23 is opened through the medium ofa follower wheel 43 when one end of the cam 44, carried by the collar38, contacts the same. It will be recalled that the switch 23 isconnected in series with the photoelectric cells 19 and 20. Thetraversal of the support 39 thus also controls actuation of thephotoelectric cells.

With the above explanation in mind, the operation of a typical cycle intraversal will be apparent. Thus, the push button 33 first is depressedin order to start the motor M and energize the solenoid 31. The solenoid31 immediately closes the switch 32 whereupon the push button 33 may bereleased. The motor M then will remain energized until the circuit isinterrupted by one or the other of the switches 41, 42. Energization ofthe motor M causes a rotation of the pulley thereof in one direction orthe other, depending upon the position of the reversing switch R.Assuming energization in a given direction, the pulley 34 and gearreduction 35 cause the screw 36 to rotate. The collars 37 and 38 thenride on the Screw and cause the support cylinder 39 to carry the sampleof fabric F past the light beam 14. As this is done, the shadow S movesacross the screen. Successive portions of the surface contour shadow ofthe piece of fabric thus are cast upon the shadow screen 18 for thebenefit of the photoelectric cells 19 and 20. When a traversal has beencompleted, the earns 40 and 44 are so positioned that the circuit to themotor M and to the photoelectric cells 19 and 20 both are opened. This,in turn, deenergizes the solenoid 31 and allows the normally open switch32 to return to its open position. The circuits then are dormant untilthe reversing switch R is reversed and the push button 31 once again isdepressed to initiate a subsequent traversal cycle.

In FIGS. 4 and 5, we have shown a simple means for tensioning the fabricF. The purpose of the tensioning means is to remove all wrinkles fromthe fabric F and thereby obtain a reading for the fabric which is knownto be free of wrinkles. The means for tensioning the sides of the fabricF may include braces and 51 attached to the supporting cylinder 39.Resilient means such as springs 52 and 53 are attached to the braces 50and 51, respectively, and attached to the other end of the springs 52and 53 are gripping means 54 and 55 which may comprise hooks or clampsor some other suitable means for gripping the fabric F. The particularmeans for tensioning the sides of the fabric to remove wrinkles in thefabric specimen are a matter of choice, and the tensioning means may bevaried to suit the particular conditions. The tensioning means, however,must engage only the sides of the fabric P so that they do not interferewith the scanning of the fabric or modify the projected line profile ofthe surface.

As seen in FIG. 5, the ends of the fabric F are also tensioned to removewrinkles and these tensioning means may include clamps and 61 which areconnected to weights 62 and 63. The weights 62 and 63 are chosen suchthat they will remove Wrinkles in a lengthwise direction of the fabric Fwithout unduly stretching the fabric. Other tensioning means may ofcourse be used and the particular tensioning means described areillustrated for simplicity.

As an example, we set forth below a chart showing the results obtainedthrough the use of our method and device with respect to some samples oftypical wash and wear broadcloth, print, sport denim, and other fabric.

Sum of sigz s i se Relaxed-tension Type of fabric Preparation of samplegitgiigearirgga or wrinkle index Vlsualratrng from wrinkle indicatorBroadcloth Pressed relaxed 8.3 8.38.0=0.3 Perfect sample no wrinkles. PMassesses a Sport denim {gigggzgigr g a 7 8:2 9.69.5=0.1 Do.

Bro cl th "$3353 133323353 ggggggg ggg 5f; 11.314.o=3.3 Good sampleslightly wrinkled. m --{httthttiitthtittitittthtfihr" at sew-ea Do.Chamber {hifittiifi 2332 1123; 323 S323; tititfifiar ii8 Broadcloththitiht 322E331 SE3 3323; tfiliiiisai" 3:: i212 tee-liegeFairemplewrmkled- Gingham lhififitfifiiitill ;Siifiiilittfilhifiisa 3::i311 Bkip deer {hiiifii $2 1523; 33B 3333; i'liififisaiii .21: fifits-14AM Bmdcmh --{htttht523E23155ft53528523:ttfttidti'ttfttfia: ttzt msamplemdlywflnkla mam sass:are;asears;reassess-.1; it; m PM {assassinsas start; the t; sateen-. at l Dov In the chart illustrated above, theaverage of the absolute successive differences as indicated by thepresent wrinkle measuring device was recorded for samples of varioustype fabrics and for different preparation of the samples. Readings wererecorded for each sample with the sample in a relaxed condition and thenin a tensioned condition to remove wrinkles only from the sample.Construction features, such as slubs, fuzz, lint, etc., remainunchanged. The diiference between these two readings were then recorded.

It will be noted that the different readings or wrinkle index for thevarious type fabrics produces comparable wrinkle index values which fallwithin defined ranges or standards of performance for the fabrics. Thus,an exact scientific evaluation of the fabric performance followingwashing but without ironing is obtained by mea urement of the wrinkles.This measurement is independent of the construction or color of thefabric and is easily correlated to acceptable standards. It will beapparent also that the apparatus can be used to inspect or evaluatesurface characteristics of any flexible web which will conform to themandrel or semi-flexible Web which can be made to conform to themandrel.

In the chart illustrated above, readings for only a single traversealong a single line profile of the fabric were recorded. Obviously, itmay be desirable to obtain readings along several line profiles atdifferent sections or directions of the fabric sample. In this case,average readings may be obtained for evaluation of the performance ofthe fabric. Additionally it may be desirable to construct a wrinkleindex which is a ratio of the recorded measurements rather than adifierence. Either means may of course be used, although the differenceindex is preferred in the present embodiment.

It will be apparent that the apparatus can be used to inspect orevaluate surface characteristics of various kinds, providing the surfaceis of a material which can be draped over the mandrel or supportingcylinder 39 and such that the material conforms to the shape of themandrel. The depth and uniformity of surface patterns on embossed paperor fabric, or on three-dimensional woven fabric, are characteristic ofthis type. Corduroy offers a specific illustration of this type of use.The esthetic value of a corduroy fabric is affected by such propertiesas the distance from one Wale to another, the amount of open spacebetween adjacent tufts, the height of the tufts, the presence ofoccasional fibers extending above the general surface, and theuniformity of these properties from one spot to another on the fabric.All of these characteristics can be detected by a beam of light shiningacross a suitably created internal edge of the fabric. Thecharacteristics can be recorded on a chart, and observed there, or, byappropriate and well known changes in the computing circuit, thesecharacteristics can be reported by one or several numbers.

In evaluating surface characteristics of materials other than wrinkledfabrics, it will be apparent that statistical measurement methods otherthan a sum of absolute successive differences may be desirable, in whichcase well known modifications may be made to the recording computercircuit. It will also be apparent that by use of a well known method ofobtaining surface impressions of inflexible surfaces with a plasticfilm, the surface characteristics of an inflexible surface may also beevaluated by the present method and device. The plastic film,

being flexible and being a true picture of the surface of the inflexiblesurface, may then be draped over the supporting cylinder 39 andevaluated or measured in the manner explained above.

In conclusion, it will be appreciated that our method and measuringdevice may be modified and used to obtain accurate measurements ofdifferent characteristics of flexible webs in the light of the foregoingteachings. It is therefore understood that changes may be made hereinwithin the full intended scope of our invention as defined by theappended claims.

We claim:

1. A method of determining an index of wrinkles in a flexible web,comprising the steps of projecting a contour profile of a line portionacross the surface of the flexible web, recording the sum of continuoussuccessive height differences of two separated points along said profilewith said web relaxed to include said wrinkles and with said webtensioned to remove said wrinkles, then taking the difference of saidtensioned and said relaxed web sums.

2. A method of determining an index of wrinkles in a flexible web,comprising the steps of creating a crest line across the surface of saidweb, projecting a contour profile of a crest line, recording the sum ofcontinuous successive height differences of two separated points alongsaid profile including said wrinkles, recording the sum of continuoussuccessive height differences of separated points along said profilewithout said wrinkles, and comparing said recorded sums to obtain anindex of said wrinkles and said web.

3. A method of determining an index of wrinkles in a. flexible web,comprising the steps of creating a crest line across the surface of saidweb, projecting a contour profile of said crest line, recording the sumof continuous successive height differences of two separated pointsalong said profile with said web relaxed to include said wrinkles andwith said web tensioned to remove said wrinkles, and then taking thedifference of said tensioned and said relaxed sums to obtain an index ofsaid wrinkles.

4. A device for determining the surface characteristics of a web offlexible material, comprising a light source directing a beam of lighttoward an image receiving means, means for supporting said web with aline portion perpendicular to and partially intercepting said beam oflight to cast a profile shadow of said line portion onto said imagereceiving means, said image receiving means including adjacently spacedlight sensitive means positioned to generate electrical signalsrespectively proportional to the height of two spaced portions of saidprofile shadow, said light sensitive means being connected to produceelectrical signals representing the difference in said heights of saidspaced portions.

5. A device for determining the surface characteristics of a web offlexible material, comprising a light source directing a beam of lighttoward an image receiving means, means for supporting said web with aline portion perpendicular to and partially intercepting said beam oflight to cast a profile shadow of said line portion onto said imagereceiving means, said image receiving means including adjacently spacedlight sensitive means positioned to generate electrical signalsrespectively proportional to the height of two spaced portions of saidprofile shadow, said light sensitive means being connected to produce anelectrical signal representing the difference of said distances, meansmoving said profile shadow relative'to said light sensitive means tocause said light sensitive means to view successive spaced portions ofsaid profile shadow across said profile to obtain an index measurementof the wrinkles in said fabric.

6. A device for determining the surface characteristics of a web offlexible material, comprising a light source directing a beam of lighttoward an image receiving means,

' means for supporting said web with a line portion perpento generateelectrical signals respectively proportional to 9 including means fortensioning said web on said supporting means along said ridge line andperpendicular thereto. 7. A device for determining the surfacecharacteristics of a web of flexible material, comprising a light sourcedirecting a beam of light toward an image receiving means,

means for supporting said web with a line portion thereof perpendicularto and partially intercepting said beam of light to cast a profileshadow of said line portion onto said image receiving means, said imagereceiving means including adjacently spaced photocells positioned togenerate electrical signals respectively proportional to the height oftwo spaced portions of said profile shadow, said photocells beingconnected to produce an electrical signal representing the difierence ofsaid heights, means for moving said support means within predeterminedlimits to cause said spaced apart photocells to view successive spacedportions along said profile shadow to produce successive differencesignals, and means summing said successive difference signals to obtainan index measurement of the wrinkles of said fabric.

8. A method of determining surface irregularities of flexible material,comprising the steps of producing a ridge line across the surface ofsaid web material, projecting a profile shadow of the line portion,utilizing the projected profile shadow to obtain a sum of successiveheight differences of two separated points continuously along saidprofile shadow.

9. A method of determining an index of wrinkles removed from' a Web offlexible material by tensioning the material, comprising the steps ofcreating a ridge line across the surface of the flexible material,projecting a profile shadow of said ridge line, utilizing the projectedprofile shadow to obtain a first sum of successive height differences oftwo separated points continuously along said profile shadow, tensioningsaid web material to remove wrinkles therein, utilizing the projectedprofile shadow of said ridge line with said web in said tensionedcondition to obtain a second sum of successive height differences ofseparated points continuously along profile shadow, and subtracting thesecond sum from said first sum to obtain an index of the wrinklesremoved in said web material by tensioning.

10. A device for measuring surface irregularities in a web of flexiblematerial comprising, a light source directing a beam of light towardsadjacently spaced light sensitive means, support means between saidlight source and said light sensitive means for supporting said web witha line portion of the web surface perpendicular to and partiallyintercepting said beam of light to cast a profile shadow of the surfaceirregularities along the line portion toward said adjacently spacedlight sensitive means, said adjacently spaced light sensitive meansreceiving spaced portions of said profile shadow and generating voltagesportional to the respective: heights of spaced portions of said profileshadow, means providing relative motion of said profile shadow and saidlight sensitive means in a direction parallel to said line portion tocast successive portions of said profile on said light sensitive meanscontinuously across said profile, and circuit means for electricallysumming continuous difference voltages as successive spaced portion ofsaid profile as viewed by said light sensitive means to obtain ameasurement of the surface irregularities in said web.

References Cited in the file of this patent

8. A METHOD OF DETERMINING SURFACE IRREGULARITIES OF FLEXIBLE MATERIAL,COMPRISING THE STEPS OF PRODUCING A RIDGE LINE ACROSS THE SURFACE OFSAID WEB MATERIAL, PROJECTING A PROFILE SHADOW OF THE LINE PORTION,UTILIZING THE PROJECTED PROFILE SHADOW TO OBTAIN A SUM OF SUCCESSIVEHEIGHT DIFFERENCES OF TWO SEPARATED POINTS CONTINUOUSLY ALONG SAIDPROFILE SHADOW.